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mackiee

macrumors member
Original poster
Mar 14, 2014
99
51
I have a brand new LG UltraFine 4K monitor connected with the Thunderbolt cable that came with the display and experience intermittent monitor black/blank outs (brief of a second) at least a couple of times a day. Most of the times it seems to happen when installing a program but I also got it when downloading a large installation file from the internet. It somewhat seems to be related to high CPU activity. But when I compile a quite large project in Xcode I have not had any problems so its definitely not reproducible by just put load on the CPU.

Anyone else that experienced the same kind of monitor blank outs?

Mac mini M1 16/512
 
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jazz1

Contributor
Aug 19, 2002
4,511
18,267
Mid-West USA
I have a brand new LG UltraFine 4K monitor connected with the Thunderbolt cable that came with the display and experience intermittent monitor black/blank outs (brief of a second) at least a couple of times a day. Most of the times it seems to happen when installing a program but I also got it when downloading a large installation file from the internet. It somewhat seems to be related to high CPU activity. But when I compile a quite large project in Xcode I have not had any problems so its definitely not reproducible by just put load on the CPU.

Anyone else that experienced the same kind of monitor blank outs?

Mac mini M1 16/512
I’ve got the same MacMini on order. I will eagerly watch this thread. I’m getting worried about the number of external monitor issues I’m reading about/seeing on YouTube. Good luck I hope someone comes up with a solution!
 
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Anonymous Freak

macrumors 603
Dec 12, 2002
5,563
1,256
Cascadia
I experienced similar with a Samsung 4K display - but only when using a low-quality HDMI cable. I can't imagine an included Thunderbolt cable having that issue!
 

lethal753

macrumors newbie
Nov 23, 2015
29
9
I have a brand new LG UltraFine 4K monitor connected with the Thunderbolt cable that came with the display and experience intermittent monitor black/blank outs (brief of a second) at least a couple of times a day. Most of the times it seems to happen when installing a program but I also got it when downloading a large installation file from the internet. It somewhat seems to be related to high CPU activity. But when I compile a quite large project in Xcode I have not had any problems so its definitely not reproducible by just put load on the CPU.

Anyone else that experienced the same kind of monitor blank outs?

Mac mini M1 16/512
I experienced similar with a Samsung 4K display - but only when using a low-quality HDMI cable. I can't imagine an included Thunderbolt cable having that issue!
I started a thread on this issue with my MBP. It has this intermittent black out for 2 seconds on Samsung 4K monitor, but only on battery power, never when plugged in.
 
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LoopsOfFury

macrumors member
Sep 12, 2015
54
90
California
I have the same issue with my LG 4K on my MBA, but it generally (only?) happens within a few minutes of waking from sleep. I don't recall it being a problem with my 4K ASUS monitor. I figure it's some kind of OS/driver bug that will be fixed in a future update.
 

mackiee

macrumors member
Original poster
Mar 14, 2014
99
51
I thought I would give an update from my side. Three days ago I switched from using the left Thunderbolt port to the right one (when looking at the back of the mini) and I have not experienced a single black/blank out since then. This makes me wonder if there could be a problem with my left port. I will use it like this a few more days and then I will switch back to the left one and see if the problem comes back.
 
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tomhigley

macrumors newbie
Nov 28, 2020
1
0
I have a brand new LG UltraFine 4K monitor connected with the Thunderbolt cable that came with the display and experience intermittent monitor black/blank outs (brief of a second) at least a couple of times a day. Most of the times it seems to happen when installing a program but I also got it when downloading a large installation file from the internet. It somewhat seems to be related to high CPU activity. But when I compile a quite large project in Xcode I have not had any problems so its definitely not reproducible by just put load on the CPU.

Anyone else that experienced the same kind of monitor blank outs?

Mac mini M1 16/512
Yes. I have two LG UltraFine monitors – 21.5-inch (4096 × 2304) – and I was using them with a Mac Mini until one of the two monitors began randomly going dark. Eventually it stopped working altogether, and I strongly suspect the problem is a bad Thunderbolt 3 connection. Unfortunately this model has just one Thunderbolt display port, and it's out of warranty. I'd love to get the monitor fixed, but so far, no lucking finding a service center. I also have a MacBook Pro, so I'm able to use it with the other LG monitor.
 

BBman

macrumors member
Jan 15, 2012
62
10
I too have the same monitor (ultrafine 4k lg) hooked up with a thunderbolt cable to a mac mini m1 and experienced the black screen flicker twice just like you describe it. I have updated to 11.0.1 and haven't noticed it since. Not sure if that fixed it, I will continue further testing
 

T00n

macrumors newbie
Sep 10, 2016
9
3
LG ultrafine 21.5 inch, MacBook Air M1, same issue. I contacted Apple, and they are gathering info/data from my MacBook. Hopefully they will figure out.
ps. format and reinstall 11.0.1 didn't fix this.
 
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robbiemc

macrumors member
Mar 16, 2012
67
35
Same here.
I have an LG 32UL750 which is six months old and it has always had these momentary blackouts.
Previously I was using this with a 16" MBP, but now Im using a 13" M1 MBP, it's still doing it.
Im using the USB-C cable that comes with the LG, so its charging at the same time.
Annoying, really.
I wonder if we can update monitor firmware?
 
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mackiee

macrumors member
Original poster
Mar 14, 2014
99
51
This may or may not have something to do with the monitor going black randomly but... Today I tested the speed of a new Samsung T7 external SSD. I first tested to connect it to the Thunderbolt port where I got the intermittent monitor blank outs. These are the resulting speeds:
Screen Shot 2020-12-02 at 17.46.11.png

Then I tested to connect the SSD to one of the USB-C ports on the LG 4K monitor. I got read and write speeds around 350 MB/s.

Finally I tested the SSD with the free Thunderbolt port on the LG 4K monitor and to my surprise I got much better speed than when the disk was connected directly to the Mac mini!
Screen Shot 2020-12-02 at 17.58.06.png

It seems that the port that gave intermittent blank outs seems to be a little slower than the other Thunderbolt port.
 
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gank41

macrumors 601
Mar 25, 2008
4,061
4,603
I’m having this issue with the M1 MBP connected to a Belkin Thunderbolt 3 Dock Pro using a Dell U2717D Monitor via Display Port.

I noticed this started happening after I had started using an app called Amphetamine. Does anyone else use that or Caffeine? I have my settings to still allow the screen to go into Screensaver and then to allow the monitor to turn off after an hour. Amphetamine still keeps the MBP going, though. The screen going black a few times seems to happen after resuming from either screensaver or sleep.

just trying to find some kind of commonality, seeing we have different monitors and some minis and some MBPs..
 

markiv810

macrumors 6502
Sep 27, 2002
378
114
India
I have a brand new LG UltraFine 4K monitor connected with the Thunderbolt cable that came with the display and experience intermittent monitor black/blank outs (brief of a second) at least a couple of times a day. Most of the times it seems to happen when installing a program but I also got it when downloading a large installation file from the internet. It somewhat seems to be related to high CPU activity. But when I compile a quite large project in Xcode I have not had any problems so its definitely not reproducible by just put load on the CPU.

Anyone else that experienced the same kind of monitor blank outs?

Mac mini M1 16/512

I am having the same issue, I am using USB-C to connect my LG 4k monitor.
 
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Mcdevidr

macrumors 6502a
Nov 27, 2013
793
368
I’m using the LG 24” ultra fine 4K and haven’t had any issues with this yet. I’m using the same port that Apple said to use to restore it when using reconfigurator 2. The port nearest the back. I wonder if both ports are equal. I’m connecting via thunderbolt and am running Ethernet and a mouse through the monitor with a dongle.
 

markiv810

macrumors 6502
Sep 27, 2002
378
114
India
I am running the 11.1 Beta and it's currently still an issue on my machine. We'll see if today's beta update helps.

I do know that this issue has received some visibility inside Apple.

Now that second beta of 11.1 is out are the issues of display graphics and bluetooth any better.
 

strangeengine

macrumors regular
Jan 30, 2017
115
81
My UF 5K came up in the correct resolution after the lasts Beta update. That's a good start.
 

sergioarista

macrumors member
Jul 7, 2010
62
19
LG ultrafine 21.5 inch, MacBook Air M1, same issue. I contacted Apple, and they are gathering info/data from my MacBook. Hopefully they will figure out.
ps. format and reinstall 11.0.1 didn't fix this.
Same here, but with intel macs so I think is more Big Sur related than m1 chip
 

strangeengine

macrumors regular
Jan 30, 2017
115
81
I have not seen an issue since I updated to 11.1 Beta 2 yesterday. It's early but this is a good start.
 

strangeengine

macrumors regular
Jan 30, 2017
115
81
So my UF 5K is now consistently coming up in 5120 x 2880 on 11.1 Beta 2, which is good. Thanks, Apple!

I am still experiencing the occasional blank-outs, though, so still a bit more work to be done.
 

newadventure

macrumors member
Jul 19, 2016
41
41
I have an LG UltraFine 5k connected to my m1 mac mini with a thunderbolt cable. I have a blank out a few times a day. I'm on the latest 11.1 beta 2
 

mackiee

macrumors member
Original poster
Mar 14, 2014
99
51
I have an LG UltraFine 5k connected to my m1 mac mini with a thunderbolt cable. I have a blank out a few times a day. I'm on the latest 11.1 beta 2
Have you tried using the other Thunderbolt port on the back of the mini M1? My blank outs disappeared when changing port. Haven't got a single blank out since.
 

nothingtoseehere

macrumors 6502
Jun 3, 2020
453
521
This thread is interesting and, of course, disturbing...

In my Windows-based office, we have these monitor blackouts from time to time. There we use Lenovos in docking stations with external monitors (Asus, Phillips, ...), and it happens with the Displayport connections, not with HDMI. Expensive cables did not help. There can be weeks without these blackouts, then next day, several ones. After 1 to 3 seconds, the picture reappears. Our IT company has no clue.

But I never ever had these issues with my Mac setup at home: MBP 13" early 2015, formerly a Dell UP 2414Q (Thunderbolt 2 to Displayport), now a LG Ultrafine 5K (Apple Thunderbolt 2 to 3 adapter).

Mac mini M1 arriving soon. We will see :oops:
 
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